Definite Descriptions and Semantic Memory* ANDREW ORTONY AND RICHARD C. ANDERSON University of Illinois at Urbana-Champaign Subjects were exposed to sentences containing "direct" and "indirect" uses of names and definite descriptions. On a subsequent recognition test incorrect rejections tended to be of sentences involving indirect uses, and false alarms to sentences involving direct uses. This finding is contrary to the predictions of models that suggest indiscriminate substitution of names for descriptions, as do those of Anderson and Bower, and Rumelhart and Norman. The implication is that models of semantic memory must incorporate distinct intensional and extensional representations to avoid semantic distortion. A definite description is a phrase which purports to uniquely identify or refer to an entity, as does, for example, The first president of the United States. A complete psychological theory of semantic memory must face the problem of how propositions involving definite descriptions are to be represented. Such expressions have been discussed by Anderson and Bower (1973), who stated: One of the more interesting features of our simulation program is the way in which it treats definite descriptions. Suppose that the parser encountered an input sentence such as "The f'trst President of the United States was a good husband." It would take the definite description "X was the first President of the United States," match that to memory, determine that X is George Washington, and then encode in memory that" George Washington was a good husband." Thus, no record would be left in HAM's memory to the effect that the assertion had been made using a definite description rather than a proper name. (p. 248) One of the reasons why Anderson and Bower think the matter of definite descriptions is interesting and important is that they believe this same procedure of substitutions underlies visual recognition as well. Rumelhart and Norman (1973) distinguish an occurrence of a definite *This work was supported in part by the National Institute of Education, under contract HEW NIE-G-74-0007. Reprints may be obtained from Professor Andrew Ortony, University of Illinois at Urbana, 1005 W. Nevada, Urbana, I11. 61801. 74 DEFINITE DESCRIPTIONS AND SEMANTIC MEMORY 75 description in what they call a "nominal sense" from its use as an "operator." When a definite description like The capital of the United States is encountered there is, they say, no problem. This is the case of an operator (in this instance, The capital oj') applying to an argument (in this case, the United States) and, like any other function, it delivers a value (Washington, D. C.). The other use they recognize would be the occurrence of the capital in a sentence like Yesterday I visited the capital. This would be the nominal sense and instead of again evaluating the description, its old value would be sought. A difficulty with this is that when the description is used as an operator one can only assume that the operator is distinguished from the argument on purely syntactic grounds. However, without a careful analysis of the preceding context this could lead to problems, for the operator might not be The capital of ( ), it might be The ( ) of the United States, with a whole range of possible arguments like capital, size, population, president, and so on. Usually contextual information is required to determine the operator. The way in which Rumelhart and Norman handle the nominal sense differs from the "operator" method only insofar as the value is looked up rather than recomputed. The mistake that they make, as do Anderson and Bower, is to imagine that it really is always necessary or appropriate to access the value. 1 The purpose of this paper is to develop and empirically test an account of names and descriptions which is adequate for psychological theory. A satisfac- tory account will require semantic memory models to maintain separate intensional and extensional representations, and to invoke pragmatic rules for determining to which kind of representation a predicate is to be attached in particular cases. The claim is that this decision ought to be based, in part, on a distinction between direct and indirect uses of referring expressions, both at the logical level, as the arguments are intended to show, and at the psychological level, as the experiment is designed to show. Although there is a long philosophical tradition of speculation and argument conceming definite descriptions, proper names, and their relationships both to one another and to the entities to which they refer or purport to refer (see, e.g., Frege, 1891, 1892; Kripke, 1972; Linsky, 1971; Russell, 1905; Strawson, 1950), for the purposes of this paper we can start with the analysis offered by Donnellan (1966). Donnellan argues that there are two uses of definite descriptions, those that he calls "referential" and those that he calls "attribu- tive." A referential use of a definite description is one in which the description serves to pick out or identify the intended referent. Contrasted with this is the attributive use of a definite description to characterize any individual who satisfies the description. In the first use, Donnellan notes, the definite description may succeed in picking out the individual even if (by chance) there is no one who ~It should be mentioned that Norman (personal communication) has indicated that they are changing the way in which the model handles definite descriptions to accommodateour objections. Bower (personal communication) has also accepted our objections. 76 A. ORTONY AND R. C. ANDERSON satisfies it, as when, for example, a man at a party is successfully identified using the description "the man drinking a martini" even though he actually has only water in his glass. This accidental success, however, would be impossible in an attributive use since the description, far from being merely a device to uniquely identify some individual, is all-important. So, if one asserts that the inventor of dynamite had a profound influence on the nature of warfare, it becomes very important that "the inventor of dynamite" is an attributive description, indeed, is the description which fits, for the meaning and the truth of the assertion depend not on whether some individual who happens to be identifiable by means of the description had a profound influence on the nature of warfare, but rather on the fact that any individual who satisfies the description would have had such an influence. From a philosophical viewpoint, Donnellan's distinction can be criticized. One difficulty is that there probably is no sharp distinction between the two uses, but rather a continuum of uses with these two representing the extremes. From a psychological perspective, however, it is possible to determine empirically if there is a psychological correlate of the distinction, and if there is, we can dismiss objections about lack of a sharp distinction as easily as we can dismiss the denial of a perceptual difference between adjacent colors on the visible spectrum (e.g., red and orange) based on the observation that there is no point at which the one ends and the other begins. We can still distinguish two colors most of the time. A general account of how models of semantic memory ought to treat names, definite descriptions, and propositions involving them can be developed on the basis of the following extension of Donnellan's analysis. If the principle that descriptions can be used both referentially and attributively is accepted, it is reasonable to suppose that names also can be employed to perform these two functions. 2 Consider first refemtial uses. A description used referentially serves the same function typically performed by a name. That is, it picks out or uniquely indentifies an individual. But if a name is available, using a description is an indirect way of identifying that individual. The direct way would be to use the name. Put in ordinary terms, people generally use names to talk about entities when they can, and when they cannot they refer to them in indirect or roundabout ways. Consider next the attributive use of descriptions and names. The attributive use of a definite description is the direct use, and one reason for calling it "direct" is that its transformational history includes a direct derivation of it from a predicate, without necessary reference to the name of the individual associated with that predicate. So, if we wish to speak about the inventor of dynamite, regardless of who he was, the definite description "The inventor of dynamite" can be directly produced from the predicate "invented dynamite" independently of, and without reference to, the name corresponding'to the entity of which it is ~Kfipke (1972) suggests this possibility in a lengthy footnote. DEFINITE DESCRIPTIONS AND SEMANTIC MEMORY 77 predicated. Our claim is that sometimes names are used indirectly, particularly in cases where it can be assumed that the hearer knows that a predicate is true of the individual whose name it is. For example, most of the things one might want to say about the first President of the United, States could be unahabiguously expressed using the name George Washington, because the description is in some sense a preferred or privileged one. To summarize, referential uses of names and attributive uses of descriptions are direct. Attributive uses of names and referential uses of descriptions are indirect. These distinctions should have empirically testable consequences, since they imply that direct uses will require less knowledge and fewer inferences than indirect ones. For illustration, consider first a direct use of a name, as in Alfred Nobel wore a fine beard. A full understanding of this sentence in no way requires that the hearer know that Nobel invented dynamite. At most it requires the knowledge, implicit in the name, that Alfred Nobel was a man.